Semiconductor devices may have a layer in which electrical characteristics are changed if the layer is oxidized or reduced. With conductive materials, such as substrate regions, silicon members, contacts, vias, and interconnects and the like, oxidation is typically to be prevented or at least minimized. Conventional materials used for conductive materials may include silicon (monocrystalline, polycrystalline, and amorphous), metals, and metal-containing compounds. Oxides of most of these materials typically are insulators. The formation of insulating oxides can result in electrical opens, which may not be desired.
In some semiconductor devices, reducing agents may pose a problem. In capacitors using oxide ferroelectric materials as the dielectric, a reducing atmosphere may cause the ferroelectric to become degraded. The ferroelectric may lose enough of its ferroelectric properties to become virtually useless as a ferroelectric capacitor. Ferroelectric capacitors appear to be more sensitive with respect to this problem than many semiconductor devices. Processing with a relatively inert ambient, such as nitrogen, argon, helium, and the like, without any oxidizing gases may still cause ferroelectric capacitors to become degraded.
In addition to ferroelectric capacitors, other semiconductor devices may have problems with reducing agents, such as hydrogen. Hydrogen may accelerate hot electron degradation of many types of electrically programmable read only memories (EPROMs) and particularly electrically erasable EPROMs (EEPROMs). Hot carrier transport through a gate or tunnel dielectric layer generally lessens the number of times the EEPROM may be cycled, wherein a cycle is the combination of a programming step and an erasing step. Also, hydrogen may react with oxygen to form moisture. Moisture in an EPROM generally causes data retention problems.